Left and right rear long members

5

Left and right inner rocker panels

11

Left and right inner B pillars

6

Center tunnel

15

Panorama tilt sunroof
The 2015 A3 sedan features an optional panorama slide/
tilt sunroof.

The roof opening is larger than that of an internally guided
sunroof and creates a particularly airy and spacious interior
feel for the occupants.

609_069b

Thermal insulation
The glass roof panel is tinted and provides additional
thermal insulation. Thermal insulation is provided by the
following reflective components:

•
•
•

The panorama slide/tilt sunroof module meets the statutory requirements for anti-pinch protection.

99 % UV radiation reflection
92 % heat radiation reflection
90 % light radiation reflection

609_083

16

Roof installation
The panorama slide/tilt sunroof is glued into the roof
opening and thus is a major factor contributing to body
rigidity.

Transverse bonded seam

609_122b

609_070

Bonded ring seam

Component overview

Glass panel

Slide/tilt mechanism

Wind deflector

Front trim
(plastic)

Cover for
sliding sunroof motor/
roll-up sun-blind

Sliding sunroof
frame
(plastic)
Roll-up sunblind

Sliding sunroof motor

Lifting arm
guide frame

609_071
17

Bumper system
Front bumper
Characteristic elements of the vehicle's front end are the
one-piece bumper cover and single-frame radiator grille.
Large air intakes are located at the lower front.

Shock
absorber

ACC radar sensor
Impact absorber
Bumper cover locking element
Radiator
grille

Front bumper cover

609_072

Underbody
The Audi A3 has a highly effective acoustic and aerodynamic underbody designed to withstand mechanical and
thermal stresses. In addition to aerodynamics, attention
was paid to sound absorption, body protection and thermal
engine management during the development phase.

The result is improved airflow around the engine and transmission capsule, the cross-members and the wheel arches,
thus allowing a low drag coefficient (cw) of 0.31 to be
achieved.

609_082

18

Passive safety
Components
The passive occupant protection system has the following
components:

•
•
•
•
•
•
•
•
•
•
•
•

Airbag control module
Driver and passenger airbags
Front side airbags
SIDEGUARD® head airbags
Driver and passenger side knee airbag
Front airbag crash sensor
Crash sensors for side impact detection in the doors
Crash sensors for side impact detection in the C pillars
Front inertia reel seat belts with electric and pyrotechnic
belt tensioners
Safety belt warning for all seats
Safety belt switches on all seats in the seat belt buckles
Safety occupancy sensor in front passenger seat
625_050

Optional equipment

•

Rear passenger side impact airbags

Key to illustration on page 20:
E24
E25
E258
E259
E609

Driver Seat Belt Switch
Front Passenger Seat Belt Switch
Driver Side Rear Seat Belt Switch
Passenger Side Rear Seat Belt Switch
Center Rear Seat Belt Switch

G452
G179
G180
G256

Front Passenger Seat Occupant Sensor
Driver Side Airbag Crash Sensor
Front Passenger Side Airbag Crash Sensor
Driver Side Rear Side Airbag Crash Sensor

G257 Passenger Side Rear Side Airbag Crash Sensor
G283 Driver Front Airbag Crash Sensor
G284 Passenger Side Front Airbag Crash Sensor
G551 Driver Belt Force Limiter
G552 Front Passenger Belt Force Limiter
G553 Driver Seat Position Sensor
G554 Passenger Seat Position Sensor
J234
J285
J533
J854
J855

19

Airbag Control Module
Instrument Cluster Control Module
Data Bus On-Board Diagnostic Interface
Left Front Seat Belt Tensioner Control Module
Right Front Seat Belt Tensioner Control Module

K19 Seat Belt Indicator Lamp
K75 Seat Belt Indicator Lamp
K145 Front Passenger Airbag Disabled Indicator Lamp
N95
N131
N132
N153
N154
N199

Driver Airbag Igniter
Front Passenger Airbag Igniter 1
Front Passenger Airbag Igniter 2
Driver Seat Belt Tensioner Igniter 1
Front Passenger Seat Belt Tensioner Igniter 1
Driver Thorax Airbag Igniter

N200
N201
N202
N251
N252
N295
N296
N297
N298

Front Passenger Thorax Airbag Igniter
Driver Side Rear Thorax Airbag Igniter
Passenger Side Rear Thorax Airbag Igniter
Driver Head Curtain Airbag Igniter
Front Passenger Head Curtain Airbag Igniter
Driver Knee Airbag Igniter
Front Passenger Knee Airbag Igniter
Driver’s Seatbelt Tensioner Igniter 2
Front Passenger Seatbelt Tensioner Igniter 2

T16

Data Link Connector

System overview

G452

625_051bx

Legend:
Powertrain CAN bus
Convenience CAN bus

Diagnosis CAN bus

Input signal
Output signal
20

Vehicle Airbags

625_050

Passenger front airbag
The 2015 A3 sedan for the North American market will
come equipped with a two-stage adaptive hybrid gas
generator front passenger airbag.

Based on accident parameters, Airbag Control Module J234
determines the time interval at which Front Passenger
Airbag Igniter 2 N132 is activated after Front Passenger
Airbag Igniter 1 N131.

Front Passenger Airbag Igniter 1 N131

Front Passenger Airbag Igniter
2 N132

21

Gas generator

Housing
625_125

New generation of connectors
A new locking style connector is used on front passenger
airbag that incorporates a ground wire connected to the
vehicle body.

Cover

The ground circuit provides protection from electro-static
discharge. The connector has been mechanically encoded
so it can only be installed in one way.

Locking element

Contact

Mechanically encoded housing

625_124

Driver and passenger knee airbags
The Audi A3 sedan is equipped with both driver and
passenger knee air bags. Both airbags use tubular hybrid
gas generators.

Driver Knee Airbag

625_122

Passenger Knee Airbag

Front Passenger Knee Airbag Igniter
N296

Knee airbag

22

Driver Front Airbag Crash Sensor G283
Passenger Side Front Airbag Crash
Sensor G284
The A3 sedan for the North American region uses two
up-front sensors for detection of front and/or rear collisions.
They work in conjunction with Airbag Control Module J234.

These sensors are accelerometers that measure the acceleration, deceleration and longitudinal direction of the
vehicle.

G284

G283

625_052

23

Front Passenger Seat Occupant Sensor
G452 Passenger Occupant Detection
System Control Module J706
The task of the seat occupancy detection system is to
determine the following:
1. If the seat is occupied by a child or if a rearward facing
child seat is installed.
2. If an adult is seated.
Passenger Occupant Detection Control Module J706 evaluates the signals from Front Passenger Seat Occupant
Sensor G452. If J706 recognizes an empty passenger seat
or that a rearward facing child seat is installed, it instructs
Airbag Control Module J234 to disable the passenger front
airbag and knee airbag.

Front passenger Airbag -disabled- Indicator Lamp K145 in
the instrument panel warns the driver of the status of the
passenger airbag and knee airbag. If Airbag Control Module
J234 has disabled these airbags based on the signals from
J706, warning lamp K145 will remain illuminated.
In addition to the warning lamp, Airbag Control Module
J234 will also issue an optical and acoustic warning if the
seat is unoccupied or if a safety belt has been unbuckled.
Detection of an unbuckled belt is determined by a signal
from Front Passenger Seat Belt Switch E25.

This means that in the event of a collision, neither the
passenger front airbag nor front passenger knee airbag
would deploy.

Dielectric material

Front Passenger Seat Occupant Sensor
G452
Electrode

Electrode

G452 is a capacitor-type sensor. A capacitor is made of two
plates (electrodes) and an insulator (dielectric), sandwiched between them.
When voltage is applied to one of the electrodes and the
other electrode is connected to the battery‘s negative
terminal, the capacitor begins to accumulate energy. The
capacitance of a capacitor can be altered by varying the size
of the electrode plate or the dielectric.

625_058

Function
With this type of occupant detection system, the vehicle
body and sensor G452 represent the two plates of the
capacitor. These components obviously do not change in
size.
The dielectric consists of the upholstery, the atmosphere,
the adjoining seat trim parts and the occupant. The capacitance will change due to the liquid content of the occupant‘s body compared to when the seat is unoccupied or if
a rear facing child seat is installed. This capacitance signal
data is interpreted by Passenger Occupant Detection
System Control Module J706 to determine if the seat is
occupied or not.

Front Passenger Seat
Occupant Sensor
G452
Passenger Occupant Detection System
Control Module
J706
625_059
24

Installation location
Seat foam

G452 is installed under the seat cover but on top of the
seat heater elements.

Front Passenger Seat Occupant
Sensor G452
625_060

Passenger Occupant Detection System
Control Module J706
In principle, J706 measures the capacitance of Front Passenger Seat Occupant Sensor G452.
The values from J128 are read cyclically by J706 and transferred to Airbag Control Module J234 via a LIN bus.

Diagnosis
J706 is connected to G452 via a coaxial cable and is supplied assembled to the factory as a unit. The coaxial cable
and the plug of the coaxial cable must not be repaired.
There are different seat variations and thus different controls module variations for J706. The software in the ECU is
matched to the respective seat.

Control module J706 and sensor G452 cannot be replaced
separately. They are matched during production. If they
are replaced, a Basic setting must be performed with the
Scan Tool. During this basic setting the serial number of the
installed components are entered into the Airbag Control
Module.

Serviceable components

Passenger Occupant Detection System
Control Module J706

Coaxial cable

Front Passenger Seat Occupant Sensor
G452

Reference
Please refer to the latest repair and parts information when replacing the seat sensor and control module.
25

625_061

Side airbag crash sensors
Retaining lugs

The side airbag crash sensors for the driver and passenger
sides (G179 and G180) are capacitive pressure sensors.
The pressure sensors have a new mounting concept and are
no longer bolted to the inner door panel The pressure
sensors are inserted into the inner door panels and then
secured into place by twisting.

Connector
housing

Gasket

Turning aid
625_146

Front safety belt tensioner
In combination with Audi pre sense basic, the 2015 Audi A3
is equipped with reversible safety belt tensioners driven by
electric motors. This is in addition to the pyrotechnic belt
tensioners.
Airbag Control Module J234 operates Left and Right Seat
Belt Tensioner Control Modules J854 and J855 as LIN
modules.
When Audi pre sense basic detects specific driving situations, signals are sent to the data bus. The airbag control
module evaluates the signals and, if necessary, instructs
the seat belt tensioner control module to partially or fully
tension the safety belts via an electric motor. For further
information on Audi pre sense, refer to the chapter on
Active safety, page 31.
The automatic safety belt retractors use rack-type pyrotechnic belt tensioners. If an automatic seat belt retractor
with seat belt tensioner control module is replaced, the
basic setting procedure must be performed using the
“Guided Fault Finding“ function.

Safety belt tensioner
control module

Reversible tensioner
with electric motor

Active belt force
limiter

Pyrotechnic safety
belt tensioner
625_086
26

Pelvic belt tensioner with locking buckle
Depending on the country version, the 2015 A3 sedan can
be equipped pyrotechnic tensioning safety belts that help
to reduce injury to the pelvic area during certain types of
collisions. The safety belts are deployed by Driver Seat Belt
Tensioner Igniter 2 N297, and Front Passenger Seat Belt
Tensioner Igniter 2 N298.
Vehicles with this style safety belts will also have a new
locking-type buckle.
In certain types of accidents, the pelvic belt tensioners, in
conjunction with the new locking buckle, help protect the
occupant in the following manner:

•
•
•
•

Lock buckle

To help separate the pelvic force from the thoracic
force
To help reduce the chest deflection force
To help limit the movement of the pelvis
To help improve the contact between the pelvis and
seat

Automatic safety belt retractor

Safety belt guide
piece

Coupling